1. Field of the Invention
This invention relates to prefabricated ceramic tile panels for use as wall or floor coverings and a process for manufacturing such panels. The invention is a laminate, one layer of which comprises an array of grouted or caulked ceramic tiles.
2. The Prior Art
Ceramic tile has long been a highly desired facing material for walls, floors, counter tops, shower stalls, and the like. It is attractive, durable, waterproof, fireproof, and easy to clean. Tiles are available in a wide variety of sizes, shapes, colors, patterns, textures, and surface finishes. They are uniquely suited to a variety of applications ranging from decorative trim in the home to hospital operating rooms.
Ceramic tile per se is relatively inexpensive, being made essentially from clay minerals fired at high temperature. Not so its installation. The conventional construction of a ceramic tile wall, for example, begins with the installation of metal lath over a vapor barrier secured to the studding. Next, a scratch coat of mortar is applied to the lath followed by an accurately leveled mortar bed for the tile. Should the scratch coat be uneven, a separate, additional leveling layer of mortar may be required. When the mortar is sufficiently set, the tiles are set in tile cement, one by one. Individual tiles must be cut using special equipment and tools to fit them to spaces requiring less than a full tile or to fit them around fixtures and the like.
A somewhat less expensive, and less desirable, method of installing ceramic tile is the so-called "thin-set" technique. This method involves the application of ceramic tile directly over substrate. Various tile adhesives or mastics are used to mount the tile to the substrate. However, unlike the lath-supported cement of "mud-set" installations, these adhesives provide no moisture barrier.
Tile setting is a skilled occupation, commanding high wages. The level of skill required, and the time-consuming nature of conventional tile installation render the process very expensive. As a result, where once entire baths were tiled, now, commonly ceramic tile is used only in those areas where it is nearly indispensable (e.g., tub surrounds and shower stalls). Unfortunately, due to the high cost of tile installation, some builders have attempted installation shortcuts in a misguided effort to save money. It is not uncommon to find tiles cemented directly to gypsum wallboard. Such improper installation techniques frequently result in expensive repairs for the homeowner when moisture eventually finds its way into the wall.
Given this situation, it is not surprising to find a number of proposed solutions to the problem in the prior art. The concept of a prefabricated tile panel which would not require any tile setting at the installation site has long been considered. However, the tile panels previously described have all proved unsatisfactory for reasons such as insufficient strength, moisture susceptibility, excessive weight, complexity of installation, and high cost. And none have met with commercial success to any significant extent.
Early attempts to solve the problem of the high cost of installed ceramic tile included such concepts as mounting ceramic tile on a backing sheet of slate. More recently, tile panels with a plastic foam core have been proposed. Wack et al., U.S. Pat. No. 3,817,012, describes a prefabricated ceramic tile building panel. The panel includes a pre-grouted layer of lightweight (3/16") ceramic tile elements bonded to a foam backer formed from rigid closed-cell plastic foam. A fiber reinforced paper backing sheet (104 in FIGS. 4--7) is attached to the rear surface of the foam backer. The preferred material for the foam backer is polyurethane, which is foamed in place in a mold. The foaming process bonds the foam to the rear surface of the tiles. A fiber reinforced sheet is added to the rear surface of the foam backer to further strengthen the panel and permit the use of a relatively thin foam layer. The preferred material for the backing sheet is a kraft paper reinforced by a glass fiber scrim (106 in FIG. 7) which is affixed to the inner side of the paper by a thin polyethylene coating. Specialized installation hardware is required to mount the tile panels and the various cove-shaped tile elements necessary for corner assemblies.
Angioletti, U.S. Pat. No. 4,415,616, describes a monolithic slab with a ceramic tile surface, polymeric grouting material between the tiles, and a synthetic resinous plate with a reinforcing fabric embedded in its rear face. The resinous plate has shavings distributed throughout the plastic. The product, intended as a flooring material which contributes to the sound-proofing and waterproofing of the resulting floor, is preferably produced in a mold formed by a box-shaped container. The plate is preferably a microcellular polyurethane foam with an insulating material such as wood shavings or a vulcanized elastomer embedded in the matrix. A fabric scrim or net is embedded in the face of the plate opposite the tiles.
Winnick, U.S. Pat. No. 3,646,180, describes a foam-cored wall panel with two fiberglass layers. The wall panel has a foam core between two fiberglass layers. One such layer bonds a layer of ceramic tiles to the foam core. Preferably, relatively thin tiles are employed so that the panel can be suspended from the building studs as a unit. Flexible grout may be installed in the cracks between tile on the front or exposed tile layer surface of the panel. The panels are formed by placing a layer of tile face down in a mold and taping the joints formed by their abutting edges with adhesive tape. Next, a fiber-glass layer is applied to the tape-covered rear surface of the tile layer. The fiberglass material includes an adhesive or bonding agent such as a polyester resin which effects adhesion to the tile layer. To form the core, a closed cell foam plastic composition of polyurethane, polyethylene, or a polystyrene is then introduced into the cavity over the cured fiberglass layer. After curing (at a controlled temperature) the foam core is smoothed and leveled by sanding. A second fiberglass layer carrying mounting means for anchoring or securing the wall panel to conventional construction is then applied to the exposed core surface. The panel thus comprises layers of tile, adhesive tape, fiberglass, foam core, and fiberglass.
Murphy, U.S. Pat. No. 3,362,119, describes a four-layer, pre-grouted tile panel. The panel has a layer of tiles, a layer of adhesive, a rigid base sheet layer, and a deformable backing layer. The tiles may be ceramic, and the base sheet is preferably asbestos fiber embedded in mineral cement. The readily deformable backing layer (15 in FIG. 3), preferably a plastic foam, comprises the rear layer of the panel. The purpose of the foam backing is to permit the panels to conform to irregular surfaces to which the panel is applied without deforming the rigid substrate. Some tiles are not assembled to the rigid base sheet to permit fasteners to be forced through the base sheet and the backing into the supporting surface or structural member.
Bartoloni, U.S. Pat. No. 3,521,418, also describes a panel with a backing support made from fibrous material impregnated by a plastic resin. The gaps between opposing edges of adjacent tiles are filled with and closed by the resin. The fibrous backing support in its original condition is approximately one-fourth inch thick. After the backing support is impregnated with the plastic resin, its thickness is reduced by approximately one half. The article described is characterized as a "monolithic slab." This slab comprises a plastic resin interposed between the decorative tile facing and the backing support made from the fibrous material. A plurality of thin, elongated reinforcing strips or rods made from fiber glass may be immersed in the resin to provide reinforcement for the backing support.
The panels described in Bartoloni are mounted to wall studs of a building structure by means of nails or other fastening devices. Like the panels described in Murphy, one side of the backing support is provided with a plurality of untiled areas corresponding to the size of a tile. Each of these areas has a hole therein to permit the mounting of the panel. After the panels are mounted, the untiled areas are covered by tiles.
Ceramic tile panels are also used in other arts. King, U.S. Pat. No. 3,444,033, describes a substitute for conventional metal armor. Ceramic tiles are adhesively applied to a laminated base, and are covered by a woven fabric. The base consists of a number of fibrous reinforcing layers embedded in a resilient polymeric composition. Typically, the base may be formed of layers of fiberglass in an epoxy or phenol-formaldehyde resin mixed with an acrylonitrile-butadiene copolymer or a polyurethane rubber cured under heat and pressure. The woven fabric may be of nylon or polyester. When the armor is struck by a bullet, this overlying fabric is said to retain the shattered pieces of the tile and prevent the fragments from coming off in the direction from which the bullet was fired. Between the individual tiles are "separators" which may be composed of paper, masking tape, cardboard, rubber and the like. Their purpose is to avoid the transmission of shock from one tile to another.
Thus, it will be appreciated that the prefabricated ceramic tile panels known in the art prior to this disclosure all relied on a core, commonly of plastic foam, or a relatively thick backing layer to impart some measure of structural strength and rigidity to the panels. These cores substantially increase the thickness of the panels, and this in turn necessitates special mounting hardware for installation.